Kohler Engine Loses Power Under Load? (We Have A Fix)

Stacy Randall
by Stacy Randall
Many Americans own lawn mowers that have Kohler engines. While they typically work very well, it is possible for the Kohler engine to lose power. Whether it be the fuel line or spark plug, let’s explore what you can do when your Kohler engine loses power.

When winter gives way to spring, it’s time to clean up the outside for garden and barbecue get-togethers. As you begin mowing unruly patches of grass, dead leaves, and the occasional twig, your lawnmower simply stops.

There are quite a few reasons why your Kohler engine loses power under load. The problem could range from faulty spark plugs to a dirty fuel line to incorrect oil levels. Try to troubleshoot the problem yourself before taking your lawnmower to a professional service center.

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Diagnosing the Problem with Your Kohler Engine

Since you may have to look at a range of issues, prepare to get down and dirty. Make sure you have the following items on hand before taking your lawnmower apart.

Tools You Need for the Job:

  • Work gloves
  • Rags
  • Protective glasses
  • Pliers
  • Screwdriver
  • Socket wrench set
  • Box / open-end wrenches
  • Adjustable wrench
  • Spark plug socket
  • Wire brush
  • Multimeter

Many consider Kohler engines some of the best engines in the market, but problems still can and will occur. Therefore, familiarity with the engine is key in assisting with the troubleshooting process. Also, figuring out the locations of the various components will also help you save time and money.

A systematic step-by-step approach will help you identify the problem and find the fix.

Step 1: Check the Fuel

Check to see if you have adequate fuel. Also, make sure you are using the right kind of fuel for your lawnmower. This step is pretty basic but often gets overlooked.

If you put the wrong fuel in the tank, drain it if the tank is full. If there is a quarter of the wrong fuel in the tank, top it off with the right fuel.

Step 2: Check the Fuel Line

Once you have determined that you have adequate fuel levels, check the fuel line for leaks, clogs, or dirt. Ensure your lawnmower is in the “off” position before removing the fuel line from the tank. Clean out any debris, if necessary, and check for hairline cracks and possible leaking.

If your lawnmower operates with a fuel pump, check this for cracks and dirt. If the internal parts are brittle and worn, you will need a replacement pump. Do not overlook your fuel filter, and make sure to clean it out and check for possible damage.

Step 3: Check the Spark Plugs

In standard lawnmowers, you should replace spark plugs every season or after every 25 hours of use. Disconnect the spark plug lead and clean the area around it to avoid getting debris in the chamber. Using your spark plug socket, remove the spark plug and clean the area with a wire brush.

If the spark plug is wet, you could be dealing with a malfunction in the choke system or water in the fuel. However, if dry, a leaking carburetor mounting gasket or a clogged carburetor needle may be your problem. If you see evidence of burns or cracks, replace the spark plug and make sure not to over-tighten.

Step 4: Check the Air Filter

Before air enters the carburetor, it goes through a filter that traps dust and other debris. If there’s a dirty air filter, it could cause the engine to sputter intermittently and die. As with spark plugs, you should replace air filters every season or after every 25 hours of operation.

If your lawnmower’s air filter consists of pleated paper, you need to replace it immediately. If it is a foam filter, you can clean it out with hot water and detergent. Make sure to let it air out and dry thoroughly before saturating it with new engine oil and installing it.

Step 5: Check the Oil Levels

Typically, you need to change the oil in lawn equipment every season or after every 50 hours of operation. Fresh, new oil is clear and amber in color. Conversely, dark oil indicates dirty oil that has pretty much lost its effectiveness at protecting the engine.

Once you have determined the oil’s freshness, check and see that it is at its proper levels. Ensure the oil level is in between the two holes of the dipstick. Over or underfilling is just as bad as old, dirty oil and could ruin an engine.

Step 6: Check the Battery

If you are dealing with a riding mower, you may need to check the battery and battery terminals. A battery in lawn equipment may lose its charge if unused for a season.

You can usually revive a battery by charging it for several hours. Use a multimeter to check for a dead battery or signs of a faulty electrical system.

Step 7: Check the Choke

If you can restart your lawnmower, the choke opens, resulting in air and gasoline movement in your carburetor. If the choke is sticky with oil and dirt, it will not open. This translates to a mower that will move poorly and eventually bog down and shut off.

Get a rag and wipe the choke and its surrounding linkages making sure to get rid of all sticky residue. For best results, spray carburetor cleaner along the shaft to loosen grit and grime. Once it turns back on, the movement should knock the dirt right off.

Make sure the choke connections are appropriately aligned and not loose. If not adjusted accordingly, the choke will not open and shut as it should, resulting in a dead engine.

Step 8: Check the Electrical Circuitry

To check the electrical circuitry, grab your trusty multimeter or voltage-ohm meter and get started. Mentally break down the electrical circuitry in sections, and check each one accordingly. Verify each section has electrical flow before moving on to the next one.

After taking these steps and your lawnmower still does not work, the problem may lie in your carburetor. However, fixing a carburetor is a more involved process and requires more time and effort. Before attempting a fix, first, clean the carburetor and its components.

How to Clean the Carburetor of Your Kohler Engine

Tools You Need for the Job:

  • Work gloves
  • Wire brush
  • Screwdriver
  • Philips flathead screwdriver
  • Oil
  • Adjustable wrench
  • Screws
  • Clean rags

Step 1: Remove the Filter

Simply pull the filter away from the top of the carburetor. If corroded, you will need to pry it loose with a screwdriver. Scrub the area with a wire brush and pop the filter back in.

Step 2: Unscrew the Choke Valve

Unscrew the choke valve with a Philips flathead screwdriver and remove the old screw. Wipe clean, then oil the choke valve around the screw. Refasten inside the carburetor using the new screw. Tap with your fingers and make sure it rotates smoothly.

Step 3: Remove and Clean the Metering Rod

You will find the metering rod in the fuel delivery compartment. Remove the rod with a wrench and discard the old bolt attached to the mechanical system. Clean the metering rod thoroughly and oil the mechanical connections. Reattach the rod using a new six-inch steel bolt and an adjustable wrench.

Step 4: Unscrew the Float Valve

Unscrew the float valve using an adjustable wrench. Clean the surrounding area with a dry cloth and check the part for damage and corrosion. If there is too much corrosion, you need to replace the float valve.

Scrub all surrounding areas around the float valve, including the fuel nozzle and the air intake section. Make sure to include the inside of the float chamber. Once done, reattach the float valve using your adjustable wrench.

After taking all these steps, if your engine still stops and starts, it may be time to call an expert.

Quick-Reference Maintenance Tips for Your Kohler Engine

Taking care to perform these easy maintenance steps will keep your Kohler engines and equipment in tiptop shape.

  • Study the owner’s manual.
  • Hose off and clean after each use.
  • Check the oil regularly.
  • Examine the filters regularly.
  • Check and change the spark plugs when needed.
  • Sharpen dull blades.
  • Check for frays and adjust loose connections.

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Related Questions

Is it better to fix my lawnmower or buy a new one?

A lawnmower fix is undoubtedly worth attempting before purchasing a new one.  More often than not, there is simply a clog in the system that disables it from operating smoothly.  Therefore, cleaning your lawnmower regularly ensures that it runs longer than one that never gets maintained.  On the other hand, if you have had your lawnmower for over a decade, it may be time to purchase a new one.  The cost of repair over time is another factor you should consider. 

How long does a lawnmower last?

With regular care, cleaning, and maintenance, a standard lawnmower can last you about 8-10 years.  However, if you don’t perform proper maintenance, expect your lawnmower to last 4-5 years.  Furthermore, if you use and abuse it heavily, you can expect its lifespan to reduce to a mere 2-3 years.   

Is a Kohler engine better than others?

Kohler manufactures small engines that have proven to last longer and tend to be better balanced compared to competitors.  Having been in existence for almost 150 years, the Kohler brand is one of the oldest engine manufacturing companies in the world today.Keep in mind the job at hand, and do your research accordingly.  Regardless of the engine brand you end up with, maintaining your engine is vital. With proper care and maintenance, your Kohler engine will last for many years to come. 

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Stacy Randall
Stacy Randall

Stacy Randall is a wife, mother, and freelance writer from NOLA that has always had a love for DIY projects, home organization, and making spaces beautiful. Together with her husband, she has been spending the last several years lovingly renovating her grandparent's former home, making it their own and learning a lot about life along the way.

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